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Diffstat (limited to 'src/devices/cpu/tms9900/tms9900.cpp')
-rw-r--r--src/devices/cpu/tms9900/tms9900.cpp64
1 files changed, 27 insertions, 37 deletions
diff --git a/src/devices/cpu/tms9900/tms9900.cpp b/src/devices/cpu/tms9900/tms9900.cpp
index 8f092a3159d..736b840d33a 100644
--- a/src/devices/cpu/tms9900/tms9900.cpp
+++ b/src/devices/cpu/tms9900/tms9900.cpp
@@ -182,11 +182,11 @@ tms99xx_device::tms99xx_device(const machine_config &mconfig, device_type type,
: cpu_device(mconfig, type, tag, owner, clock),
m_program_config("program", ENDIANNESS_BIG, data_width, prg_addr_bits),
m_setoffset_config("setoffset", ENDIANNESS_BIG, data_width, prg_addr_bits),
- m_io_config("cru", ENDIANNESS_BIG, 8, cru_addr_bits),
+ m_io_config("cru", ENDIANNESS_LITTLE, 8, cru_addr_bits + 1, 1),
m_prgspace(nullptr),
m_cru(nullptr),
m_prgaddr_mask((1<<prg_addr_bits)-1),
- m_cruaddr_mask((1<<cru_addr_bits)-1),
+ m_cruaddr_mask((2<<cru_addr_bits)-2),
m_clock_out_line(*this),
m_wait_line(*this),
m_holda_line(*this),
@@ -1637,55 +1637,45 @@ void tms99xx_device::register_write()
void tms99xx_device::cru_input_operation()
{
- int value, value1;
- int offset, location;
+ offs_t cruaddr = m_cru_address & m_cruaddr_mask;
+ uint16_t value = 0;
- location = (m_cru_address >> 4) & (m_cruaddr_mask>>3);
- offset = (m_cru_address>>1) & 0x07;
-
- // Read 8 bits (containing the desired bits)
- value = m_cru->read_byte(location);
-
- if ((offset + m_count) > 8) // spans two 8 bit cluster
+ for (int i = 0; i < m_count; i++)
{
- // Read next 8 bits
- location = (location + 1) & (m_cruaddr_mask>>3);
- value1 = m_cru->read_byte(location);
- value |= (value1 << 8);
+ // Poll one bit at a time
+ bool cruin = BIT(m_cru->read_byte(cruaddr), 0);
+ if (cruin)
+ value |= 1 << i;
- if ((offset + m_count) > 16) // spans three 8 bit cluster
- {
- // Read next 8 bits
- location = (location + 1) & (m_cruaddr_mask>>3);
- value1 = m_cru->read_byte(location);
- value |= (value1 << 16);
- }
- }
+ if (TRACE_CRU) logerror("CRU input operation, address %04x, value %d\n", cruaddr, cruin ? 1 : 0);
- // On each machine cycle (2 clocks) only one CRU bit is transmitted
- pulse_clock(m_count<<1);
+ // Increment the CRU address
+ cruaddr = (cruaddr + 2) & m_cruaddr_mask;
- // Shift back the bits so that the first bit is at the rightmost place
- m_value = (value >> offset);
+ // On each machine cycle (2 clocks) only one CRU bit is transmitted
+ pulse_clock(2);
+ }
- // Mask out what we want
- m_value &= (0x0000ffff >> (16-m_count));
+ m_value = value;
}
void tms99xx_device::cru_output_operation()
{
- int value;
- int location;
- location = (m_cru_address >> 1) & m_cruaddr_mask;
- value = m_value;
+ offs_t cruaddr = m_cru_address & m_cruaddr_mask;
+ uint16_t value = m_value;
// Write m_count bits from cru_address
- for (int i=0; i < m_count; i++)
+ for (int i = 0; i < m_count; i++)
{
- if (TRACE_CRU) logerror("CRU output operation, address %04x, value %d\n", location<<1, value & 0x01);
- m_cru->write_byte(location, (value & 0x01));
+ if (TRACE_CRU) logerror("CRU output operation, address %04x, value %d\n", cruaddr, BIT(value, 0));
+
+ // Write one bit at a time
+ m_cru->write_byte(cruaddr, BIT(value, 0));
value >>= 1;
- location = (location + 1) & m_cruaddr_mask;
+
+ // Increment the CRU address
+ cruaddr = (cruaddr + 2) & m_cruaddr_mask;
+
pulse_clock(2);
}
}